The present invention provides a process for producing electrolytic, pure iron in an unprecedented state previously unexplored and/or utilized. Specifically, the process can produce an iron material that offers an alternative to industrial, hard, electrolytic chromium, as well as many other coating procedures.
Many processes and variations of processes for the electrodeposition of hard iron are to be found in literature. Electrolytic hard iron has been produced and utilized for a number of years, but its use has usually been limited to applications where wear resulting from lack of lubrication was not a consideration, i.e., previous processes were able to produce hard iron that was dense with no or limited controlled lubrication. Previous procedures to induce oil containing reservoirs, which are desirable, if not necessary, in most applications, have been mechanical, laser, or electrochemical etch in nature.
According to the invention, a process of producing a new, hard, electrolytic iron plating is provided. The iron plating can be applied to a metal surface of virtually any type of part, for example, engine parts or soldering tips. After a part to be plated is prepared for plating, it is placed in an iron electroplating bath. An electrolytic plating bath from which a new, hard, electrolytic iron can be produced is maintained to be composed of the following:
200-500 Gm/L Ferrous Sulfate;
20-70 Gm/L Ferrous Fluoborate;
10-35 Gm/L Ammonium Chloride; and
an effective amount of wetting agent
in an aqueous solution, where Gm/L is units of grams per liter. Wetting agents are well known in the art, and new wetting agents are developed from time to time. For example, the wetting agent can be selected from the group consisting of sodium salts of the fatty alcohol sulfates or mixtures of such salts, equivalent surface active agents, or any combination thereof. For example, an effective amount of wetting agent is 0.2-0.8 Gm/L sodium lauryl sulfate.
The pH of the plating bath is maintained in the range of 1.5 to 4.2 and adjusted with sulfuric acid and/or fluoboric acid. The temperature of the bath is maintained in the range of 100xc2x0 F. to 160xc2x0 F. Current density is relatively low and maintained in the range of 2 to 60 amps/sq.ft.(A.S.M.)
According to one aspect of the invention, the pH is changed within the specified pH range during the electroplating to at least partially control the microstructure of the electrodeposited iron. For example, if the pH is stepped or ramped down, the microstructure of the electrodeposited iron tends to change from a relatively dense iron plating base to an increasingly porous and channeled iron plating producing a desirable surface with a microstructure having reservoirs and channels.
According to a second aspect of the invention, the temperature is changed within the specified temperature range during the electroplating to at least partially control the microstructure of the electrodeposited iron. For example, if the temperature is stepped or ramped down, the microstructure of the electrodeposited iron tends to change from a relatively dense iron plating base to an increasingly porous and channeled iron plating producing a desirable surface with a microstructure having reservoirs and channels.
According to a third aspect of the invention, the current density is changed within the specified range during the electroplating to at least partially control the microstructure of the electrodeposited iron. For example, if the current density is stepped or ramped up, the microstructure of the electrodeposited iron tends to change from a relatively dense iron plating base to an increasingly porous and channeled iron plating producing a desirable surface with a microstructure having reservoirs and channels. All current used throughout the process is D.C. in nature. The part is cathodic and an iron-based anode is used.
It has been discovered that using two or more of these inventive techniques together produces synergistic results. For example, changing the pH, temperature, and current density is especially useful in controlling the nature of the build of the iron deposit and the resulting microstructure of the iron plating.
Plating time is based on the current density and the desired thickness of the iron deposit.
It is to be understood that the steps of the process need not be performed in any particular order. These and other aspects of the invention will be apparent to a person of ordinary skill in the art upon reading the following detailed description of a presently preferred embodiment and best mode of practicing the invention.